Issue 28: Residential Sprinklers Required in the International Residential Code
By Morgan J. Hurley, P.E.
Following years of attempts to require residential sprinklers in the International Residential Code,1 the 2009 edition will require residential sprinklers in all new one- and two-family homes and townhouses. The International Residential Code
requires the installation of residential sprinklers in townhomes
effective upon adoption of the code, and in one- and two-family homes
effective January 1, 2011.
The United States differs from many countries in that fire safety
codes and standards are not developed by the federal government. The
U.S. Constitution leaves the development of building safety standards to
the states. Most states do not write their own building safety
standards; instead they use "model" codes that are written by private
organizations. These "model" codes may be adopted in whole or with
amendments by states and local jurisdictions.
The 2009 edition of the International Residential Code
requires that residential sprinklers be installed in accordance with
NFPA 13D or a simplified design procedure that is provided within the International Residential Code. NFPA 13D, Standard for the Installation of Sprinkler Systems in One- and Two-Family Dwellings and Manufactured Homes, contains requirements for the design and installation of sprinkler systems, such as discharge rates and installation criteria.
During the development of the 2009 edition of the International Residential Code
(IRC), eleven proposals were submitted pertaining to residential
sprinklers. Nine of these contained requirements for the installation of
residential sprinkler systems, while two provided suggested simplified
design criteria for residential sprinkler systems.
Two of the proposals would have required the installation of
sprinklers in all new one- and two-family homes and townhouses effective
upon the adoption of the code, while one proposal would have required
sprinklers in all new one- and two- family homes and townhouses
effective January 1, 2011. One proposal would have required sprinklers
in all townhouses, but not in one- and two-family homes, while another
would have required sprinklers in all townhouses and provided incentives
for the installation of sprinklers in one- and two-family homes. One
proposal would have required sprinklers in all new one- and two-family
homes and townhouses that are made using lightweight construction (such
as wooden I-beams or trusses) unless the lightweight construction was
protected by a 30 minute barrier.
The other three proposals would have also provided incentives for the
installation of sprinklers in one- and two- family homes and
townhouses, but not require them. Ultimately, the IRC took differing
approaches for one- and two-family homes and for townhouses so that
local jurisdictions and the sprinkler installation industry could
prepare for the requirement to take effect. These preparations might
include training for sprinkler installers and training and certification
A 2007 study by the National Institute of Standards and Technology
found that the benefits associated with residential sprinkler systems
outweighed the costs.2 This study investigated the costs of
installing sprinkler systems in three types of houses: one- and
two-story freestanding single-family residences, and a townhouse. A
multipurpose network system made using cross-linked polyethylene (PEX)
tubing was selected for use to develop cost estimates, as it was found
to be less expensive than other types of residential sprinkler systems.
These costs were compared with the expected benefits of having a
residential sprinkler system, which included avoided deaths and
injuries, avoided uninsured property losses, indirect costs, and
reductions in homeowners' insurance premiums. Costs and benefits were
compared using a common metric (dollars), and a sensitivity analysis was
Notarianni and Fischbeck3 also analyzed the costs and
benefits of mandating residential sprinklers as a function of housing
type (one- or two-family, multiple family or mobile home) community
size, region of the country and whether the mandate would apply to new
or existing homes. Notarianni and Fischbeck considered the installation
costs, reduction in direct and indirect losses, reduction in injuries to
occupants and fire fighters and the number of fire related fatalities
that would be averted by installing residential sprinklers.
Notarianni and Fischbeck calculated with 90 percent confidence that
the cost to society associated with a residential sprinkler mandate
would be in the range of $4.2 million to $10.7 million per averted fire
death, with a median value of $7.3 million (USD).
The City of Scottsdale, Arizona, was an early jurisdiction to require
residential sprinklers, when it passed a residential sprinkler
ordinance in 1985. Experience in Scottsdale over the 15 years following
adoption of their residential sprinkler ordinance has shown that
residential sprinkler systems reduced fire related property loss by an
order of magnitude, and avoided 13 fatalities in a city with a
population of just under 220,000.4
Prince George's County, Maryland, adopted a residential sprinkler ordinance in 1987. A study5
examining fires which occurred in structures from 1989 to 1999 found
that 154 fatalities and approximately $40 million dollars (US) in
property loss had been avoided during this almost 11 year period. (It is
noteworthy that the losses investigated in this study were not limited
to residential structures.)
Opponents to requiring residential sprinkler systems cited the
potential damage from freezing pipes or accidental discharge, the
unavailability of an adequate water supply in some areas among the
reasons why residential sprinklers should not be required.
While the IRC has now been amended to require residential sprinklers
in one- and two-family homes and townhouses, this does not mean that all
future homes of these types will be equipped with residential
sprinklers. The 2009 edition of the IRC must be adopted by local states
and jurisdictions for this requirement to carry the force of law. The
same organizations that opposed the requirement for residential
sprinklers in the IRC development process have now shifted their efforts
to local code adoption processes. Ultimately, legislative bodies within
local states and jurisdictions will have the final say, and the result
might be inconsistent approaches among U.S. states and jurisdictions.
Morgan Hurley is with the Society of Fire Protection Engineers.
International Residential Code, International Code Council, Washington, D.C., 2009.
Butry, D., Brown, M. H., and Fuller, S., "Benefit-Cost Analysis of
Residential Fire Sprinkler Systems," NISTIR 7451, National Institute of
Standards and Technology, Gaithersburg, MD, 2007.
Notarianni, K., and Fischbeck, P., "A Methodology for the Quantitative
Treatment of Variability and Uncertainty in Performance-Based
Engineering Analysis and/or Decision Analysis with a Case Study in
Residential Fire Sprinklers," Proceedings – 1998 Pacific Rim
Conference and Second International Conference on Performance-Based
Codes and Fire Safety Design Methods, Society of Fire Protection Engineers, Bethesda, MD, 1998.
Ford, J., "15 Years of Built-in Automatic Fire Sprinklers: The
Scottsdale Experience," Rural/Metro Fire Department, Scottsdale, AZ,
Siarnicki, R., "Residential Sprinklers: One Community's Experience
Twelve Years After Mandatory Implementation," Prince George's County
Fire Department," 2001.
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